U.S. patent number 4,942,925 [Application Number 07/396,563] was granted by the patent office on 1990-07-24 for liner isolation and well completion system.
This patent grant is currently assigned to Dresser Industries, Inc.. Invention is credited to Daniel J. Themig.
United States Patent |
4,942,925 |
Themig |
July 24, 1990 |
Liner isolation and well completion system
Abstract
In a wellbore having a liner hung from a higher string of pipe,
a permanent packer and a seal unit are utilized to isolate the
annulus between the liner and the wellbore surface. The downhole
completion assembly, which comprises an on-off tool, a latch and
seal assembly and a tailpipe, can be lowered into the packer and
seal unit by the production tubing, with the latch mechanism of the
latch and seal assembly snapping into a threaded portion of the
packer. The on-off tool can be disconnected and the production
tubing withdrawn from the well. Alternatively, the latch mechanism
can be disengaged and the entire downhole completion assembly can
be withdrawn from the well in a single trip.
Inventors: |
Themig; Daniel J. (Oklahoma
City, OK) |
Assignee: |
Dresser Industries, Inc.
(Dallas, TX)
|
Family
ID: |
23567736 |
Appl.
No.: |
07/396,563 |
Filed: |
August 21, 1989 |
Current U.S.
Class: |
166/382; 166/123;
166/134; 166/208; 166/237; 285/18 |
Current CPC
Class: |
E21B
17/06 (20130101); E21B 23/02 (20130101); E21B
43/10 (20130101); E21B 33/1293 (20130101); E21B
33/12 (20130101) |
Current International
Class: |
E21B
17/06 (20060101); E21B 17/02 (20060101); E21B
43/02 (20060101); E21B 43/10 (20060101); E21B
33/12 (20060101); E21B 33/129 (20060101); E21B
23/00 (20060101); E21B 23/02 (20060101); E21B
023/00 (); E21B 023/06 (); E21B 033/129 () |
Field of
Search: |
;166/382,387,237,380,134,123,208,369 ;285/18,144,146,147 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Novosad; Stephen J.
Claims
I claim:
1. In a wellbore which transverses various earth formations, a
first string of pipe for lining a first vertical portion of said
wellbore, said first string of pipe having a lower end which is
above the bottom of said wellbore, a second string of pipe for
lining a second vertical portion of said wellbore, said second
vertical portion extending downwardly from said lower end of said
first string of pipe, each of said first and second strings of pipe
having an axial bore therethrough, the outer diameter of said
second string of pipe being smaller than the inner diameter of said
first string of pipe, a polished bore receptacle and liner hanger
assembly connected to the upper end of said second string of pipe
and having a fluid passageway therethrough, said assembly having a
liner hanger positioned within the bore of said first string of
pipe and in mechanical engagement with the interior surface of the
bore of a lower portion of said first string of pipe to suspend
said second string of pipe from said lower portion of said first
string of pipe, said assembly having a polished bore receptacle
with a polished interior bore forming at least a portion of said
passageway,
the improvement comprising
a tubular packer positioned within the bore of said first string of
pipe at a location above said assembly, said packer having at least
one gripping means in frictional engagement with the interior
surface of the bore of said first string of pipe to immobilize said
packer in said first string of pipe, said packer having a tubular
element with an internal bore extending axially therethrough, at
least one annular packer seal extending circumferentially about
said tubular element and in contact with the interior surface of
the bore of said first string of pipe to provide a fluid seal
between the exterior surface of said tubular element and the
interior surface of the bore of said first string of pipe,
a seal unit having a tubular member and at least one annular seal
extending circumferentially about said tubular member, said seal
unit being positioned in said polished interior bore with said at
least one annular seal of said seal unit being in contact with said
polished interior bore to form a fluid seal between said tubular
member and said polished bore receptacle, means for connecting the
upper portion of said tubular member of said seal unit to the lower
portion of said tubular element of said packer,
a string of tubing positioned within the bore of said first string
of pipe, an on-off tool having a first sleeve and a second sleeve,
means for connecting said first sleeve to the lower end of said
string of tubing, means for releasably securing said first sleeve
to said second sleeve,
a latch and seal assembly having latching means in engagement with
the upper portion of said tubular element of said packer, and
having a tubular section extending downwardly from said latching
means within said tubular element of said packer, at least one
annular seal extending circumferentially about said tubular section
and in contact with the interior surface of the internal bore of
said tubular element of said packer to provide a fluid seal between
the exterior surface of said latch and seal assembly and the
interior surface of said internal bore of said packer, means for
connecting said latch and seal assembly to said second sleeve of
said on-off tool, a tailpipe, and means for connecting said
tailpipe to the lower portion of said tubular section, whereby the
only fluid communication between the interior of said second string
of pipe and the interior of said string of tubing is through said
tailpipe, said latch and seal assembly and said on-off tool.
2. Apparatus in accordance with claim 1 wherein said means for
releasably securing said first sleeve to said second sleeve
comprises:
one of said first and second sleeves having a J shaped slot therein
and the other of said first and second sleeves having a projection
thereon which is adapted to project into and slide within said slot
between a first position wherein said first and second sleeves are
thereby secured together and a second position wherein said first
and second sleeves are separated from each other.
3. Apparatus in accordance with claim 2 further comprising at least
one profile nipple in said tailpipe, whereby a plug can be lowered
through said string of tubing into said tailpipe to engage said
profile nipple and thereby seal the interior of said second string
of pipe from the interior of said tailpipe above the thus plugged
profile nipple.
4. Apparatus in accordance with claim 3 wherein, in said polished
bore receptacle and liner hanger assembly, said polished bore
receptacle extends above said liner hanger.
5. Apparatus for isolating the annulus around a wellbore liner and
for achieving down-hole completion in a wellbore which transverses
various earth formations, which comprises:
a first string of pipe positioned in said wellbore to serve as a
liner for a first portion of said wellbore, said first string of
pipe having an axial bore therethrough, the lower end of said first
string of pipe being above the bottom of said wellbore,
a second string of pipe, means for hanging said second string of
pipe from within the bore of the lower portion of said first string
of pipe to serve as a liner for a second portion of said wellbore,
said second portion extending downwardly from the lower end of said
first string of pipe, said second string of pipe having an axial
bore therethrough, the outer diameter of said second string of pipe
being less than the inner diameter of the bore of said first string
of pipe,
a tubular member extending upwardly from a first position within
the bore of said second string of pipe to a second position within
the bore of said first string of pipe above the upper end of said
second string of pipe,
at least one first annular seal between a lower portion of said
tubular member, located within said second string of pipe, and the
interior surface of the bore of the laterally adjacent portion of
said second string of pipe,
at least one second annular seal between an upper portion of said
tubular member, located above said second string of pipe, and the
interior surface of the bore of the laterally adjacent portion of
said first string of pipe,
a third string of pipe positioned within the bore of said first
string of pipe, said third string of pipe having on the lower end
thereof an on-off tool, a latch and seal assembly connected to the
lower end of said on-off tool, and a tailpipe extending downwardly
from said latch and seal assembly, said latch and seal assembly
being positioned within said tubular member, and said tailpipe
extending at least partially into the bore of said second string of
pipe,
said latch and seal assembly releasably securing said latch and
seal assembly to said tubular member and providing a fluid seal for
the annulus between the interior surface of tubular member and the
exterior surface of said latch and seal assembly.
6. Apparatus in accordance with claim 5 wherein said on-off tool
comprises a first sleeve and a second sleeve, one of said first and
second sleeves having a J shaped slot therein and the other of said
first and second sleeves having a projection thereon which is
adapted to project into and slide within said slot between a first
position wherein said first and second sleeves are thereby secured
together and a second position wherein said first and second
sleeves are separated from each other, means for connecting said
first sleeve to the lower end of said third string of pipe, and
means for securing said second sleeve to said latch and seal
assembly.
7. Apparatus in accordance with claim 6 wherein said tubular member
and said at least one second annular seal constitute a packer.
8. Apparatus in accordance with claim 7 further comprising at least
one profile nipple in said tailpipe.
9. A method of isolating the annulus around a wellbore liner and
for achieving downhole completion in a wellbore which transverses
various earth formations, which comprises:
installing a first string of pipe in said wellbore to serve as a
liner for a first portion of said wellbore, said first string of
pipe having an axial bore therethrough, the lower end of said first
string of pipe being above the bottom of said wellbore,
hanging, from within the lower portion of said first string of
pipe, a second string of pipe to serve as a liner for a second
portion of said wellbore, said second portion extending downwardly
from the lower end of said first string of pipe, said second string
of pipe having an axial bore therethrough, the outer diameter of
said second string of pipe being less than the inner diameter of
the bore of said first string of pipe,
positioning a tubular member so that it extends upwardly from a
first position within the bore of said second string of pipe to a
second position within the bore of said first string of pipe above
the upper end of said second string of pipe,
providing an annular seal between a lower portion of said tubular
member, located within said second string of pipe, and the interior
surface of the bore of the laterally adjacent portion of said
second string of pipe,
providing an annular seal between an upper portion of said tubular
member, located above said second string of pipe, and the interior
surface of the laterally adjacent portion of said first string of
pipe,
lowering through the axial bore of said first string of pipe a
third string of pipe, having on the lower end thereof an on-off
tool, a latch and seal assembly connected to the lower end of said
on-off tool, and a tailpipe extending downwardly from said latch
and seal assembly, until said latch and seal assembly is positioned
within said tubular member and said tailpipe extends at least
partially below the bore of said tubular member, and
activating said latch and seal assembly to releasably secure said
latch and seal assembly to said tubular member and to provide a
fluid seal for the annulus between the interior surface of tubular
member and the exterior surface of said latch and seal
assembly.
10. A method in accordance with claim 9 further comprising
producing fluid from at least one of said earth formations by
passing fluid from the bore of said second string of pipe through
said tailpipe, said latch and seal assembly, said on-off tool and
said third string of pipe to above ground production
facilities.
11. A method in accordance with claim 9 further comprising
inserting a plug in said tailpipe, activating said on-off tool to
disconnect said third string of pipe from said latch and seal
assembly, and withdrawing said third string of pipe from the
wellbore while the interior of the bore of said second string of
pipe below said tailpipe is isolated from the interior of the bore
of said first string of pipe.
12. A method in accordance with claim 9 further comprising causing
said latch and seal assembly to become released from said tubular
member, and, thereafter simultaneously withdrawing said third
string of pipe, said on-off tool, said latch and seal assembly and
said tailpipe from said wellbore.
13. A method of achieving downhole completion in a wellbore which
transverses various earth formations,
a first string of pipe having been installed in said wellbore to
serve as a liner for a first portion of said wellbore, said first
string of pipe having an axial bore therethrough, the lower end of
said first string of pipe being above the bottom of said
wellbore,
a second string of pipe having been hung from within the lower
portion of said first string of pipe, to serve as a liner for a
second portion of said wellbore, said second portion extending
downwardly from the lower end of said first string of pipe, said
second string of pipe having an axial bore therethrough, the outer
diameter of said second string of pipe being less than the inner
diameter of the axial bore of said first string of pipe, a tubular
member having been positioned in said wellbore extending upwardly
from a first position within the axial bore of said second string
of pipe to a second position within the axial bore of said first
string of pipe above the upper end of said second string of pipe,
said tubular member having an annular seal between a lower portion
of said tubular member, located within said second string of pipe,
and the interior surface of the laterally adjacent portion of said
second string of pipe, said tubular member having an annular seal
between an upper portion of said tubular member, located above said
second string of pipe, and the interior surface of the laterally
adjacent portion of said first string of pipe, which comprises the
steps of:
lowering through the axial bore of said first string of pipe a
third string of pipe, having on the lower end thereof an on-off
tool, a latch and seal assembly connected to the lower end of said
on-off tool, and a tailpipe extending downwardly from said latch
and seal assembly, until said latch and seal assembly is positioned
with said tubular member and said tailpipe extends at least
partially below the bore of said tubular member, and
activating said latch and seal assembly to releasably secure said
latch and seal assembly to said tubular member and to provide a
fluid seal for the annulus between the interior surface of tubular
member and the exterior surface of said latch and seal
assembly.
14. A method in accordance with claim 13 further comprising
producing fluid from at least one of said earth formations by
passing fluid from the bore of said second string of pipe through
said tailpipe, said latch and seal assembly, said on-off tool and
said third string of pipe to above ground production
facilities.
15. A method in accordance with claim 13 comprising inserting a
plug in said tailpipe, activating said on-off tool to disconnect
said third string of pipe from said latch and seal assembly, and
withdrawing said third string of pipe from the wellbore while the
interior of the bore of said second string of pipe below said
tailpipe is isolated from the interior of the bore of said first
string of pipe.
16. A method in accordance with claim 13 further comprising causing
said latch and seal assembly to become released from said tubular
member, and thereafter simultaneously withdrawing said third string
of pipe, said on-off tool, said latch and seal assembly and said
tailpipe from said wellbore.
Description
TECHNICAL FIELD OF THE INVENTION
This invention relates to method and apparatus for use in oil field
completion operations involving liner hanger systems. In one
particular aspect, the invention relates to method and apparatus
for isolating a well liner and for completing the well for high
pressure service.
BACKGROUND OF THE INVENTION
The drilling of an oil well generally involves drilling the
borehole in successive stages with each stage having a borehole
diameter which is less than the borehole diameter of the preceding
stage As each of the upper stages of the borehole is drilled, a
string of tubular casing pipe is inserted into the borehole,
extending from the earth's surface to a location adjacent the
current bottom of the borehole. This string of casing pipe is
generally cemented in place The column of cement, in the annulus
formed by outer surface of the casing pipe and the borehole wall,
supports the casing pipe and at least substantially prevents fluid
migration along the annulus. Then a smaller diameter drill is
lowered through the casing and the next stage of the borehole is
drilled. Eventually extending the new casing all the way from the
earth surface becomes undesirable, and then the newest borehole
stage is cased by lowering a string of liner pipe into the borehole
and hanging this liner from the lower end of the lowermost string
of pipe already in the borehole, followed by cementing the liner in
place. The drilling, lining and cementing operations can continue
until the desired depth is achieved.
To position and cement a liner in a string of casing, the liner is
made up with the usual bottom hole equipment which includes a
casing shoe, float collar and plug catchers and is connected up to
the desired length. At the top of the liner is a liner hanger which
is an assembly having slip elements which are normally retracted
while going into the borehole and which are released downhole when
setting of the liner hanger is desired. The liner hanger is lowered
into the borehole by a setting tool which attaches to the liner
hanger and a string of pipe attached to the setting tool. At the
desired location where the casing shoe is preferably located above
the bottom of the open borehole, the liner hanger is set in the
next above casing by actuating the setting tool to set the slips on
the liner hanger. Upon setting the liner hanger, the weight of the
liner is suspended by the liner hanger on the next above casing.
The setting tool is released and the liner hanger is then cemented
by pumping cement through the string of pipe and through the liner
and into the annulus between the liner and borehole After the
cement is set up, any remaining cement in the liner can be removed
by drilling through the liner and destructible cement equipment at
the lower end of the liner. When the open borehole reaches the
projected well depth and traverses the formations to be completed,
the liner includes a liner hanger and oftentimes a polished bore
receptacle (PBR). The polished bore receptacle attaches either
above or below the liner hanger and provides a bore to receive a
sealing member on a production tubing string.
The production string of tubing, which has a sealing element
adapted to be slidingly and sealingly received in the polished bore
receptacle, extends from the earth's surface. When the well is
completed, fluids from the earth formation being produced flow
through the tubing string to the production equipment at the
earth's surface. The sealing element on the string of tubing is
subjected to downhole hydraulic pressure forces, and the tubing
string is subjected to expansion and contraction forces due to
changes in the temperature of the fluid in the tubing string. The
purpose of a sliding seal on a string of tubing in a polished bore
receptacle generally is to permit movement of the seal and the
string of tubing relative to the polished bore receptacle.
When the producing formation is at high pressure conditions, it is
possible for high pressure fluid to seep through the annular sleeve
of concrete which exists between the outside of the liner and the
surrounding earth formation. Such seepage can rise and enter the
annular gap between the overlap of the top of the liner in the
producing formation and the bottom of the next higher cemented
string of pipe. In the absence of any sealing mechanism for the
annular gap, the high pressure fluid can fill the annulus between
the production tubing and the casing. The production tubing can
have a higher pressure rating for a lower cost than the casing pipe
because of the relatively small diameter of the production tubing
compared to the diameter of the casing pipe. Accordingly, it is
generally desirable to reduce costs by using casing pipe with a
substantially lower pressure rating than the production tubing
Thus, leakage of the high pressure fluid into the annulus between
the production tubing and the casing can cause damage to the lower
pressure rated casing.
One solution for the leakage problem is to install a packer to seal
the annular gap between the liner and the casing, in combination
with a second polished bore receptacle (PBR) positioned within the
packer to seal off the annulus between the production tubing and
the liner. Each PBR can be as much as thirty feet long and is very
expensive due to the manufacturing requirements for its polished
interior surface. In many downhole completions using a permanent
packer, the tailpipe is run as part of the packer assembly and
becomes a permanent part of the well, unless the permanent packer
is also removed. The presence of the tailpipe in the wellbore
restricts access to the liner because of the small size of the
tailpipe. Some downhole completions utilize a landed seal assembly,
but this requires two trips to retrieve.
Accordingly, it is an object of the present invention to provide
new and improved method and apparatus for isolating a liner and
providing a seal between production tubing and the liner. Another
object of the invention is to permit the downhole production
completion assembly to be disconnected from the liner isolation
seal and be removed from the borehole in a single trip. A further
object of the invention is to permit the removal of the production
tubing from the borehole while maintaining a high pressure seal
between the producing formation and the borehole casing above the
producing formation. Other objects, aspects and advantages of the
invention will be apparent from the following description, the
drawings and the appended claims to the invention.
SUMMARY OF THE INVENTION
The annulus around a wellbore liner can be isolated by positioning
a tubular member within the liner with the tubular member extending
upwardly from a first position within the axial bore of the liner
to a second position within the axial bore of the next higher
string of pipe above the upper end of the liner. The tubular member
can be provided with a first annular seal between the tubular
member and the liner, and a second annular seal between the tubular
member and the next higher string of pipe. The downhole completion
can be achieved by lowering a string of production pipe, having on
the lower end thereof an on-off tool, a latch and seal assembly
connected to the lower end of the on-off tool, and a tailpipe
extending downwardly from the latch and seal assembly, until the
latch and seal assembly is positioned within the tubular member and
said tailpipe extends at least partially below the bore of the
packer. The latch and seal assembly can then be activated to
releasably secure the latch and seal assembly to the tubular member
and to provide a fluid seal for the annulus between the interior
surface of tubular member and the exterior surface of said latch
and seal assembly.
Production fluid from the producing formation can be withdrawn via
the tailpipe, the latch and seal assembly, the on-off tool, and the
string of production pipe. When it is desirable to pull the
production tubing, a plug can be inserted into the tailpipe to seal
off the producing formation, the on-off tool can be activated for
separation of the production tubing from the downhole completion
assembly, and the production tubing can then be withdrawn from the
borehole while leaving the producing formation at high pressure
condition. If access to the wellbore below the tailpipe is desired,
the downhole completion assembly can be withdrawn by activating the
latch and seal assembly to release from the tubular member, and
retrieving the downhole completion equipment in a single trip.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a vertical sectional view of a well bore which has been
lined by successively smaller diameter pipe strings cemented in
place, with at least the lowermost pipe string being a liner which
has been hung from a lower portion of the next higher pipe
string;
FIG. 2 corresponds to the lower portion of FIG. 1 with an isolation
packer and seal unit, shown partially in cross section, having been
lowered into place by a drill pipe string and hydraulic setting
tool; and
FIG. 3 corresponds to FIG. 2 after the packer has been set in
place, the hydraulic setting tool has been removed and production
completion assembly has been lowered into place by the production
tubing.
DETAILED DESCRIPTION
Referring now to FIG. 1, a borehole 10 extends vertically
downwardly into the earth traversing various formations, including
at least one producing formation. The borehole 10 has been drilled
in a plurality of stages 11, 12 and 13 with each stage having a
smaller borehole diameter than the immediately preceding stage. A
string of casing pipe 14 was inserted into upper borehole stage 11
and secured in place by the formation of cement sleeve 15 filling
the annular space between the exterior surface of casing 14 and the
adjacent exposed earthen surface of the borehole. Similarly, a
string of casing pipe 16 was inserted into intermediate borehole
stage 12 and secured in place by the formation of cement sleeve 17,
with the lower end of string 16 being substantially above the
ultimate bottom of borehole 10. Thus, pipe string 14 serves as a
liner or casing for the vertical portion of wellbore 10 represented
by first stage 11, while pipe string 16 serves as a liner or casing
for the vertical portion of wellbore 10 represented by intermediate
stage 12.
A string of liner pipe 18 has been positioned in the lower borehole
section 13. Unlike casings 14 and 16, which extend to the earth
surface and are directly connected to the wellhead 19, liner 18
extends upwardly only into the lowermost portion of the next higher
pipe string 16. Each of pipe strings 14, 16 and 18 has an axial
bore therethrough at least generally parallel to the axis of
borehole 10. The external diameter of pipe string 18 is less than
the internal diameter of the bore of pipe string 16. Similarly, the
external diameter of pipe string 16 is less than the internal
diameter of the bore of pipe string 14. Liner string 18 is
initially suspended from the lowermost portion of pipe string 16 by
means of a conventional liner hanger assembly 21 positioned within
the bore of string 16. Assembly 21 achieves a mechanical engagement
with the inner surface of the bore of pipe string 16 and the outer
surface of liner string 18. The liner string 18 can then be
cemented in place by the formation of cement sleeve 22, in the same
manner as the casing strings 14 and 16 were cemented in place.
Thus, pipe string 18 serves as a liner for the vertical portion of
wellbore 10 which extends downwardly from the lower end of pipe
string 16.
In addition to the liner hanger assembly 21, the string 18 of liner
pipe is also provided with a relatively short polished bore
receptacle (PBR) 23. In contrast to the approximately 30 foot
length of many PBR's intended for use as a telescoping joint, the
PBR 23 can be on the order of only six feet in length. PBR 23 has
an upper bore section 24 which is highly polished and a lower bore
section 25 which has a smaller internal diameter than upper bore
section 24. A normal liner pipe 26 is attached to the lower end of
PBR 23. The liner string 18 can be made up with the PBR 23 above
the liner hanger assembly 21, as illustrated, or with the liner
hanger assembly 21 above the PBR 23. While the cement sleeve 22 is
shown as extending upwardly only to the bottom of casing string 16
for simplicity of illustration, it is generally customary for the
cement 22 to continue upwardly to the top of the liner string 18,
including the PBR 23 and liner hanger assembly 21. As the cement
sleeve 22 is not completely impermeable to well fluids, it is
possible for fluids under sufficiently high pressure at the bottom
of the borehole 10 to seep upwardly through cement sleeve 22 and
into the interior of casing 16.
Referring now to FIG. 2, a seal unit 31 is connected by extension
sleeve 32 and crossover 33 to the bottom of tubular isolation
packer 34. The tubular member 35 of seal unit 31 has an external
diameter which is slightly smaller than the internal diameter of
the upper bore section 24 of PBR 23, and is provided with a
plurality of circumferentially extending seals 36 to contact the
interior surface of bore section 24 and thereby seal the annular
space between the exterior of seal unit 31 and the interior surface
of bore section 24. Isolation packer 34 is provided with at least
one expandable elastomeric ring 37 extending circumferentially
about the tubular member 30 of packer 34 and which has been
subjected to compression in a direction parallel to the
longitudinal axis of borehole 10 by suitable actuating means to
cause the annular ring 37 to expand radially outwardly into sealing
engagement with the interior surface of the bore of the laterally
adjacent portion of pipe string 16. Packer 34 is also provided with
slip mechanisms 38 and 39 extending circumferentially about tubular
member 30 and which have been moved radially outwardly into
frictional engagement with the interior surface of the bore of pipe
string 16 to immobilize the packer 34 in pipe string 16.
A conventional hydraulic setting tool 41 is in threaded engagement
with the upper end of packer 34 and is secured to the lower end of
drill pipe or tubing 42 by a crossover section 43 and extension 44.
Packer 34 and seal unit 31 can be lowered into borehole 10 by drill
pipe or tubing 42 and setting tool 41 until seal unit 31 has
entered and sealingly engaged the polished bore 24 of PBR 23.
Setting tool 41 can then be utilized to cause elastomeric ring 37
to sealingly engage the interior surface of the bore of pipe string
16 and to cause slips 38 and 39 to mechanically grip the interior
pipe surface of the bore of string 16. Such engagement by slips 38
and 39 prevents movement of packer 34 upwardly or downwardly in
pipe string 16. After the packer 34 has been activated, the drill
pipe 42 can be rotated to unscrew setting tool 41 from packer 34,
and the drill pipe 42 and setting tool 41 can be withdrawn from the
borehole 10. The packer 34, crossover 33, tubular extension 32 and
seal unit 31 isolate the annulus between the exterior surface of
PBR 23 and the interior surface of the bore of pipe string 16 from
the interior of pipe string 18 and from the interior of pipe string
16 above packer 34, while permitting fluid communication between
the interior of pipe string 18 and the interior of pipe string 16
above packer 34 via their axial bores.
Referring to FIG. 3, the setting tool 41 has been removed from the
well bore 10 and the downhole production completion assembly has
been positioned in place. A latch seal assembly 51 has a latch seal
nipple 52, a seal unit 53, and a crossover unit 54. The latching
elements of the latch seal nipple 52 snap into engagement with the
threads on the female collar at the top of the tubular member 30 of
packer 34 when the latch seal assembly is lowered into the packer
34. The latch seal assembly 51 can be rotated to unscrew it from
the packer 34, permitting the latch seal assembly to be removed
from the well bore if that becomes necessary. A tubular tailpipe
55, having profile collars 56 and 57 therein, is secured to the
lower portion of crossover unit 54.
An on-off tool 58 is connected between the lower end of production
tubing 59 and the upper end of latch seal assembly 51. The on-off
tool 58 has an outer tubular skirt 61 secured to the lower end of
production tubing 59 by suitable means, e.g. threaded engagement.
Tool 58 has an inner tubular skirt 62 secured to the upper end of
latch seal assembly 51 by suitable means. The on-off tool 58 has a
bore 60 therethrough which is approximately coaxial with the bore
of production tubing string 59, the bore latch seal assembly 51,
and the bore of tailpipe 55 to provide fluid communication between
the bore of liner 18 and the bore of production tubing string 59.
Skirt 61 has an upside-down J-shaped groove 63 cut in its interior
surface, while skirt 62 is provided with a pin 64 which projects
outwardly therefrom into groove 63. A plurality of annular seals 66
are positioned on the exterior of tubular element 62 in sealing
engagement with the interior surface of outer tubular element 61 in
a region axially spaced from the slot 63. Thus, outer tubular
element 61 is movable axially with respect to inner tubular element
62, from a first position with sleeves 61 and 62 being releasably
secured to each other to a second position wherein sleeves 61 and
62 are separated from each other. This is accomplished by pin 64
sliding in the long leg of the slot 63, and seals 66 providing a
fluid seal between the exterior of inner element 62 and the
interior of outer element 61 during engagement of sleeves 61 and
62. Alternately, the production tubing 59 and outer tubular element
61 can be lowered to place the pin 64 at the curved arc of the slot
63 and then the tubing 59 and element 61 can be rotated a
quarter-turn, thereby permitting tubing 59 to be raised, separating
outer sleeve 61 from the inner sleeve 62.
Slot 63 can be a groove having a depth less than the thickness of
sleeve 61, or it can extend through the sleeve 61. While the slot
63 and pin 64 have been illustrated on sleeves 61 and 62,
respectively, they can be reversed if desired.
The downhole completion assembly, comprising on-off tool 58, latch
seal assembly 51 and tailpipe 55, can be attached to the lower end
of production tubing string 59 and lowered into the wellbore until
the latch seal assembly 51 is positioned within tubular element 30
and tailpipe 55 extends at least partially below the bore of the
packer. The latch seal assembly can then be activated to engage the
threaded portion of packer 34 to releasably secure the latch seal
assembly to packer 34. Production fluid from the producing
formation can be passed from the bore of liner 18 through tailpipe
55, latch seal assembly 51, on-off tool 58 and production tubing 59
to the above ground production facilities.
If it is desirable to removing the tubing string 59 while the
production is still viable, a plug can be lowered through the
production tubing 59 and inserted into one of the profile nipples
56, 57 in tailpipe 55 to seal off the producing formation. Then the
on-off tool 58 can be rotated to disconnect the production tubing
59 from latch seal assembly 51, and the production tubing 59 can be
withdrawn from the well. If for any reason it is desired to
retrieve the latch seal assembly 51 and tailpipe 55, the tubing
string 59 can be rotated to unscrew the latch seal assembly from
the packer 34, and then the tubing 59, on-off tool 59, latch seal
assembly 51 and tailpipe 55 can be withdrawn in a single trip of
the tubing.
Each of liner hanger 21, PBR 23, packer 34, seal unit 31, latch
seal assembly 51, tailpipe 55 and on-off tool 58 can be any
suitable device which is commercially available for the intended
purpose. While the devices selected can vary according to the size
and other environmental limitations, one suitable combination for
isolating and completing a 4-1/2" liner hung from a 7"casing, with
a 2-7/8" production tubing, is as follows:
______________________________________ Device Commercially
Available Equipment ______________________________________ On-off
tool 58 7" .times. 27/8" Guiberson XL on-off tool with 3 bonded
seals (10,000 psi pressure rating), model #89207, with a 2.313"
type, X profile nipple Latch seal 51 4" .times. 27/8" latch seal
assembly containing a Guiberson model #83089 latch seal nipple, a
one foot seal unit model #83082, and a crossover to 27/8" tubing
thread Packer 34 7" .times. 4.00" Guiberson bore magnum "GT"
drillable packer, model #82063 Tailpipe 55 One 10' .times. 27/8"
N-80 tubing pup, one 2.313" type "XN" profile nipple with 2.205"
no-go, and one wireline re-entry collar.
______________________________________
The on-off tool can be released by slacking off on the tension on
tubing 59, rotating tubing 59 1/4 turn to the left and then raising
tubing 59. The on-off tool 58 can be automatically reset by
slacking off on the tubing 59 with the two sleeves of the on-off
tool contacting each other, and then pulling tension to insure that
the tubing is latched. The latch seal 51 can be released by pulling
500 pounds tension and then rotating tubing 59 eight turns to the
right. The latch seal automatically reseats upon being lowered into
contact with the threads of packer 34 and slacking off of the
tension of tubing 59. This system can be used for stimulation,
production or workover operations. Reasonable variations and
modifications are possible within the scope of the foregoing
description and the appended claims to the invention.
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